Both animal feed and fertilisers can contain radionuclides and have an impact on the food chain. They are therefore regularly analysed by our laboratories as part of laboratory-based environmental monitoring.

The radionuclides caesium-137, radium-226 and thorium-232 are of particular importance in feed analyses.

Caesium-137 was only detected in 8 % of the samples. Most of these samples were of organic origin and the caesium-137 probably originated from the radioactive fallout after the Chernobyl disaster. The activity concentrations of caesium-137 were between 0.2 and 6.2 Bq/kg.

Radium-226 is a naturally occurring radionuclide that is produced in the decay cycle of uranium-238 and is found in minerals containing uranium. Radium-226 was detected in about 39 % of the samples. The activity concentrations were between 0.3 and 90 Bq/kg. The highest levels were found in mineral feedstuffs, premixes and additives.

Thorium-232 is a naturally occurring radionuclide contained in minerals such as monazite and thorite. Thorium-232 was detected in about 20 % of the samples, with activity concentrations between 0.3 and 82 Bq/kg. Similar to radium-226, the highest levels were measured in mineral feedstuffs, premixes and additives.

In 2024, the focus of our measurements was on poultry feed. The highest values for radium-226 and thorium-232 were found in an additive at 37.5 Bq/kg and 42 Bq/kg respectively. However, as additives only make up a small percentage of the total amount consumed (usually approx. 1%), this value is harmless. The artificial radionuclide caesium-137 could not be detected in any of the samples. No health-relevant values were detected.

Fertilisers are used to supplement the nutrient supply for cultivated plants. In addition to heat, light, air and water, plants also need nutrients to grow. These nutrients are often not present in the soil in an optimally utilisable form and quantity. They are either washed out of the soil or extracted from it in considerable quantities by the cultivated plants. The addition of plant nutrients through fertilisation makes it possible to replace the lost nutrients. Further general information on fertilisers can also be found here.

The radionuclides contained in fertilisers can be absorbed by the cultivated plants and thus enter the food cycle. We therefore regularly test fertilisers as part of our laboratory-based environmental monitoring. Different types of fertilisers (mineral and organic) as well as growing media (soils) and plant additives (e.g. rock flour) are tested. Mineral fertilisers contain nutrients in the form of salts that can be directly absorbed by plants (e.g. nitrogen, phosphorus and potassium). Organic fertilisers consist of natural raw materials such as compost, manure or slurry. The nutrients they contain are converted in the soil by microorganisms.

We analyse around 50 fertiliser samples every year. A total of 424 samples were analysed between 2016 and 2024. The radionuclides analysed include natural radionuclides such as potassium-40, radium-226 and thorium-232 as well as the artificial radionuclide caesium-137.

In 2024, the highest values for radium-226 were measured in an NPK fertiliser at 611 Bq/kg. NPK fertilisers contain the three main nutrients nitrogen (N), phosphorus (P) and potassium (K). The highest value for potassium-40 was found to be 9397 Bq/kg in a mineral compound fertiliser (PK fertiliser). The highest values for thorium-232 and caesium-137 were detected in growing media (vegetable soil, humus soil), with thorium-232 reaching a value of 23 Bq/kg and caesium-137 a value of 17 Bq/kg.

In Austria, approx. 100 kg of fertiliser (mineral fertiliser) is applied annually per hectare of conventionally farmed land worthy of fertiliser. If only the fertilisers with the highest measured concentrations were applied, the activity per square metre would be as follows: 6 Bq/m² for radium-226, 93 Bq/m² for potassium-40, 0.23 Bq/m² for thorium-232 and 0.17 Bq/m² for caesium-137.

The radioactivity released is negligible and not relevant to health.